Studies on a Distributed Database System in Personal Computer Network

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The major objective in this research is to establish a construction method for the operating systems which provide effective functions for the database processing. This is because there are several performance problems of database systems on a conventional operating system. In this fiscal year, we have implemented a prototype system on the experimental system which consists of several personal computers connected by a local area network, and evaluated the performance of the software segmentation and stream-oriented relational operations which were studied in the last year. Furthermore, in this yoar, we have studied the following research subjects : 1. Exception handling in the tnansaction processing, 2. Duplicate executions of the transaction, 3. Server for monitoring network communications, 4. Visual user interface based on the tabular form, 5. Micro-mainframe link. In the above subject 1, we have studied the processing scheme of exceptional events in the distributed environment where all the network site are connnected by a local area network, and developed system primitives for the distributed exception handling. In the subjcet 2 and 3, we have studied a general procedure for the recovery from the failures of transaction, site, and communication link. In the subject 4 and 5, we have implemented the TCP/IP protocol as a network protocol of the prototype system. Furthermore, by using the X-window system on UNIX, we have implemented part of user interface of the prototype system on the UNIX workstation, and confirmed the possibility of sharing of the user interface task between several processors.